(1) Field of the Invention
The present invention generally relates to a microwave oven. More particularly, it relates to a microwave oven which includes an opening, formed on one side panel of the microwave oven's inner case, through which high frequency energy produced by a magnetron is introduced into a cooking chamber, and a cover plate for sealing the opening to prevent dirt and dust from getting into the cooking chamber, pervious to the high frequency energy.
(2) Description of the Prior Art
A microwave oven is a cooking appliance that cooks food by frictional heat generated by making the molecules of the food being cooked move at high speeds with the use of high frequency energy. FIG. 4 is a sectional view of the interior construction of a conventional microwave oven.
As shown in FIG. 4, the conventional microwave oven includes an inner case 20 in which a cooking chamber 30 is formed, and an outer case 10. The inner case 20 has a front panel 21, a rear panel 22 and right and left side panels 23, thus constituting the cooking chamber 30. Also, there is a tray 31 at the bottom of the cooking chamber 30 and an opening in the front panel 21 of the cooking chamber 30. The outer case 10 is connected to the ends of the front panel 21 and the rear panel 22 of the inner case 20, thus constituting the main body of the microwave oven. This outer case 10 is spaced away from the side panels 23 of the inner case 20. A door 50 is hinged on one side of the front panel 21 of the inner case 20 to open and close the cooking chamber 30, and a control portion 51 is provided to the right side of the front panel 21.
An electrical component compartment 40, in which various electrical components are installed, is provided in the space between the right side panel 23 of the inner case 20 and the right side panel 11 of the outer case 10. In the electrical component compartment 40 are mounted a magnetron 42 for producing high frequency energy to the cooking chamber 30, and a fan 41 for cooling off the electrical components that emit heat during operation.
The magnetron 42 is connected to the right side panel 23 of the inner case 20, facing the electrical component compartment 40, and an opening 23c is formed on the right side panel 23 through which high frequency waves enter the cooking chamber 30. A cover plate 60 comes in contact with the right side panel 23 to cover the opening 23c inside of the cooking chamber 30. More specifically, as shown in FIG. 5, the cover plate 60 is coupled to the right side panel 23 by the use of a curved portion 61 and an elastic piece 62, and this coupling structure is now described in detail.
As shown in the drawing, the opening 23c is positioned on the middle of the right side panel 23 to allow the electrical component compartment 40 to communicate with the cooking chamber 30, and holes 23a and 23b are respectively formed on the lower and upper sides of the opening 23c. The magnetron 42 is installed on the right side panel 23 in the electrical component compartment 40, and emits the high frequency waves to the cooking chamber 30 through the opening 23c. The curved portion 61 and the elastic piece 62 are respectively formed on the lower and upper sides of the cover plate 60's back to mate with the holes 23a and 23b. As the elastic piece 62 is placed into the hole 23b after the curved portion 61 has been fitted into the hole 23a, the front ends of the hook 61 and the elastic piece 62 come in close contact with the right side panel 23 on the side of the electrical component compartment 40, thus securely fixing the cover plate 60 onto the right side panel 23. Also, the edges of the cover plate 60 are beveled. The microwaves produced by the magnetron 42 are furnished to the cooking chamber 30 through the opening 23c and the cover plate 60, and the cover plate 60 keeps the dirt and dust from sticking to the magnetron 42.
In such a conventional microwave oven, the right side panel 23 may be deformed in the process of welding the magnetron 42 onto the right side panel 23 or when the curved portion 61 and the elastic piece 62 are respectively inserted into the holes 23a and 23b during coupling of the cover plate 60. Once the right side panel 23 gets distorted, the cover plate 60 may not lie flush on the side panel, thereby creating a gap between the cover plate 60 and the side panel 23 in which dirt and dust can collect. The dirt and dust in the gap cause an electric spark that decreases the reliability of the microwave oven thereby.